Step 1: Prepare the Cake Batter

1. Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans or line them with parchment paper.
2. In a large mixing bowl, sift together the flour, cocoa powder, sugar, baking soda, baking powder, and salt.
3. Add the buttermilk, vegetable oil, eggs, and vanilla extract to the dry ingredients. Mix on medium speed until combined.
4. Slowly pour in the boiling water while mixing on low speed. The batter will be thin—this ensures a moist cake.

Step 2: Bake the Cakes

1. Divide the batter evenly between the prepared pans.
2. Bake for 30–35 minutes, or until a toothpick inserted into the center comes out clean.
3. Allow the cakes to cool in the pans for 10 minutes before transferring them to a wire rack to cool completely.

Step 3: Make the Oreo Cream Cheese Frosting

1. In a large bowl, beat the softened butter and cream cheese together until smooth and fluffy.
2. Gradually add the powdered sugar, one cup at a time, mixing well after each addition.
3. Stir in the vanilla extract, then fold in the crushed Oreo cookies.

Step 4: Assemble the Cake

1. Place one cake layer on a serving plate or cake stand. Spread a thick layer of Oreo cream cheese frosting over the top.
2. Place the second cake layer on top and spread a thin crumb coat of frosting over the entire cake. Chill for 20 minutes to set.
3. Frost the entire cake with the remaining frosting, smoothing the sides and top with a spatula.

Step 5: Garnish and Serve

1. Decorate the cake with additional crushed Oreos, whole cookies, or chocolate shavings if desired.
2. Slice and serve chilled or at room temperature.